Rootin, a compound that inhibits root development through modulating PIN-mediated auxin distribution

Abstract

tPlant roots anchor the plant to the soil and absorb water and nutrients for growth. Understanding themolecular mechanisms regulating root development is essential for improving plant survival and agricul-tural productivity. Extensive molecular genetic studies have provided important information on crucialcomponents for the root development control over the last few decades. However, it is becoming diffi-cult to identify new regulatory components in root development due to the functional redundancy andlethality of genes involved in root development. In this study, we performed a chemical genetic screen toidentify novel synthetic compounds that regulate root development in Arabidopsis seedlings. The screenyielded a root growth inhibitor designated as ‘rootin’, which inhibited Arabidopsis root development bymodulating cell division and elongation, but did not significantly affect shoot development. Transcriptanalysis of phytohormone marker genes revealed that rootin preferentially altered the expression ofauxin-regulated genes. Furthermore, rootin reduced the accumulation of PIN1, PIN3, and PIN7 proteins,and affected the auxin distribution in roots, which consequently may lead to the observed defects in rootdevelopment. Our results suggest that rootin could be utilized to unravel the mechanisms underlyingroot development and to investigate dynamic changes in PIN-mediated auxin distribution.